The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
In motor vehicle automatic transmissions, it is necessary to constantly provide a flow of lubricating transmission fluid to a significant number of rotating components. Determining the necessary lubrication flow which may also be defined as a minimum or sufficient flow for a given component or group of components is critical. Providing such necessary flow is a challenge since it must be maintained throughout the operating speed range of the transmission. Accordingly, flow control devices such as orifices and passageways are sized to provide sufficient flow at high RPM in spite of the fact that, so sized, they will provide excessive flow at low RPM. While this worst case engineering solution fully satisfies the lubrication requirement, an acknowledged consequence is that energy is wasted providing the unnecessarily high flow at low RPM. Specifically, such excess flow causes increased parasitic losses from the internal components of the transmission such as open clutches, bearings, bushings, rotating shells and the like. These parasitic losses result in increased fuel consumption.
It goes without saying that a design arrived at through compromise is more problematic. Attempting to find a middle ground between minimum necessary flow at high RPM and excessive flow at low RPM will, in all likelihood, result in components at least marginally starved for lubrication at high RPM which may compromise performance and service life.
The foregoing summary of the state of the automatic transmission lubrication art suggests that improvements in this art would be desirable and the present invention is so directed.